Optical fibers are commonly used today for the transmission of signals of all sorts, including communication and data signals. Optical fibers can be single mode fibers (typically employed in long-distance communication), which have only one strong propagation mode, or multi-mode fibers, in which light transmitted in the different modes arrives at different times, resulting in dispersion of the transmitted signal.
Single mode fibers transmit signals between transceivers (i.e., devices that can both transmit and receive optical signals) via pairs of fibers. More specifically, one fiber of the pair will transmit signals from the first transceiver to the second, and the other fiber of the pair will transmit signals from the second transceiver to the first. In this manner, optical signals are not traveling along the same fiber in different directions, as such activity could interfere with both signals.
This pairing arrangement would be fairly simple to organize for two transceiver devices that are permanently optically connected, but in practice transceivers are typically connected through a much larger network of optical fibers, connectors and patch panels. For example, a common optical system includes multiple transceivers at one end, patch cord pairs that are connected to the transceivers and to a duplex adapter mounted on a patch panel, a fan-out unit connected to the duplex adapter that connects to a multi-fiber fiber optic cable (12 fibers per cable is common, and the cable is often in ribbon form) via an array adapter, a second fan-out unit connected to the opposite end of the cable via a second array adapter, and corresponding transceivers connected via patch cord pairs to the second fan-out unit through another duplex adapter. Thus, clearly it is important to be able to track individual optical fibers in the various devices and cables between the transceivers in order to ensure that the individual transceivers are connected as desired.
To ensure intermateability of cabling components and signal polarity, standards have been created to define arrangements of fibers, cables, adapters and connectors. For example, one such standard for array connectors, TIA-604-5B, is directed to MPO fiber optic connector intermateability. Another standard, TIA 568-B.3 with addendum No. 7 written by committee TR-42.8, is directed to maintaining optical fiber polarity with systems using array connectors and adapters, including MPO's. This addendum discusses three different methods of creating an optical path from the transmit side of one transceiver to the receive side of another transceiver. These methods, termed Methods A-C, are intended to “link multiple duplex optical transceiver ports or to link two parallel optics transceiver ports . . . ” Systems built using these methods utilize fiber optic cables, adapters, transitions and patch cords that are typically partially or completely unique to one of these methods.
Each of the methods has its own benefits and drawbacks. As such, it may be desirable to provide additional connectivity methods and components suitable for use with such methods.